I was a ticking time bomb. But now I have hope.
On May 4th, 2025, in a Los Angeles operating room, surgeons crossed a threshold that medicine had long considered unreachable — successfully transplanting a human bladder for the first time in history. A 41-year-old man named Oscar Larrainzar, who had spent seven years unable to urinate normally after cancer stripped him of his kidneys and most of his bladder, walked away from the procedure with restored function and no need for dialysis. The achievement matters not only for what it gave one man, but for what it may eventually offer the millions worldwide for whom bladder failure has meant a life of cascading, unresolvable compromise. In medicine, as in human experience, the first time something impossible is done is the moment it ceases to be impossible.
- After seven years tethered to dialysis machines and catheters, Oscar Larrainzar had nearly exhausted every option medicine could offer him.
- The surgical team spent over four years rehearsing on deceased donors, engineering new techniques to navigate the bladder's dense, vessel-laden anatomy — a region so complex it had kept transplantation off the table entirely.
- The existing alternative — repurposing intestinal tissue as a bladder — fails in roughly 80% of patients due to a fundamental biological incompatibility between the digestive and urinary microbiomes.
- Within hours of the eight-hour operation, the transplanted kidney produced urine immediately, dialysis became unnecessary, and Larrainzar urinated normally for the first time in seven years.
- Four additional transplants are now planned as part of a formal clinical trial, with larger trials to follow if results hold — placing a once-unthinkable treatment on the path toward broader availability.
On May 4th, 2025, surgeons at a Los Angeles hospital completed the world's first successful bladder transplant, implanting a donor kidney and bladder into 41-year-old Oscar Larrainzar during an eight-hour procedure. Larrainzar's history was one of relentless loss: cancer had forced the removal of both his kidneys and most of his bladder, leaving him with an organ capable of holding less than two tablespoons of fluid. For seven years, dialysis machines filtered his blood while catheters managed what little remained of his urinary function.
The surgical team, led by urologists Nima Nassiri and Inderbir Gill, had spent more than four years preparing — practicing on deceased donors and developing a key innovation: pre-connecting veins and arteries before implanting the donor organ, reducing the procedure's complexity without sacrificing its integrity. The bladder's anatomy, a tangle of blood vessels buried deep in the abdomen, had long made transplantation seem nearly impossible.
The results were immediate and unambiguous. The transplanted kidney produced urine within hours. Dialysis was no longer needed. Larrainzar could urinate normally — something his body had not done in seven years. The significance extends far beyond one patient: the current surgical alternative, repurposing intestinal tissue as a bladder replacement, fails in roughly 80% of cases because the digestive and urinary tracts carry incompatible microbiomes, creating chronic complications. A transplanted bladder sidesteps all of that.
Four more transplants are planned as part of a clinical trial, with larger studies to follow if outcomes hold. Recipients must commit to long-term immunosuppressive therapy, so the procedure remains reserved for those with no other viable path. At a follow-up visit, Larrainzar told his doctors: 'I was a ticking time bomb. But now I have hope.' That hope, once unimaginable for someone in his condition, now reaches toward the millions still waiting.
On May 4th, a surgical team at a Los Angeles hospital completed a procedure that had never been attempted on a living human before: transplanting a bladder from a deceased donor into a patient whose own organ had failed. The eight-hour operation involved retrieving both a kidney and bladder from the donor, then carefully implanting them into a 41-year-old man named Oscar Larrainzar, who had spent the previous seven years tethered to dialysis machines.
Larrainzar's medical history was brutal. Years earlier, cancer had forced surgeons to remove both his kidneys and most of his bladder. What remained of his bladder could hold only 30 milliliters of fluid—less than two tablespoons—compared to the 700 milliliters a healthy bladder can accommodate. For seven years, he had been unable to urinate normally, dependent on dialysis to filter waste from his blood and on catheters to manage what little function remained. He was, by any measure, running out of options.
The surgical team, led by urologists Nima Nassiri and Inderbir Gill, had spent more than four years preparing for this moment. They practiced the procedure repeatedly on deceased donors still on ventilators, developing new techniques to navigate the bladder's treacherous anatomy—a web of blood vessels buried deep in the abdomen that had made transplantation seem nearly impossible. The key innovation was pre-connecting some of the veins and arteries before implanting the donor organ, a simplification that reduced the procedure's complexity without compromising its success.
Within hours of surgery, the results were unmistakable. The transplanted kidney began producing urine immediately. Larrainzar's kidney function improved at once, eliminating the need for dialysis. More remarkably, he could urinate normally—something his body had not done in seven years. "The kidney immediately made a large volume of urine, and the patient's kidney function improved immediately," Nassiri reported. "There was no need for any dialysis after surgery, and the urine drained properly into the new bladder."
The breakthrough matters because millions of people worldwide live with severe bladder dysfunction, and until now, the only surgical option was to repurpose a section of the patient's intestine to serve as a replacement bladder. This workaround, however, fails in roughly 80 percent of cases. The problem is fundamental: the digestive tract and urinary tract operate with entirely different microbiomes, and forcing them to coexist creates cascading complications—digestive problems, kidney damage, chronic infections. A functioning transplanted bladder, if it could be made to work, would avoid all of that.
Larrainzar's case proved it could work. The surgical team plans to perform four more transplants as part of a clinical trial. The catch is significant: bladder transplant recipients must already be taking, or be willing to take, long-term immunosuppressive medications to prevent organ rejection. These drugs carry their own risks and side effects, which is why the procedure is currently reserved for patients with no other viable options—people like Larrainzar, for whom the alternative was a life of dialysis and severe functional limitation.
If the next four cases proceed as successfully as the first, a much larger trial will follow, potentially transforming how medicine approaches terminal bladder disease. During a follow-up appointment, Larrainzar told his doctors something simple and profound: "I was a ticking time bomb. But now I have hope." That hope, once unimaginable for someone in his condition, now extends to millions of others waiting to see whether this historic surgery can be repeated, refined, and made available to those who need it most.
Notable Quotes
The kidney immediately made a large volume of urine, and the patient's kidney function improved immediately. There was no need for any dialysis after surgery.— Urologist Nima Nassiri, UCLA
This surgery is a historic moment in medicine and stands to impact how we manage carefully selected patients with highly symptomatic terminal bladders.— Urologist Inderbir Gill, USC
The Hearth Conversation Another angle on the story
Why did it take so long to attempt this? Bladder transplants seem like they should have been tried decades ago.
The anatomy is genuinely difficult. The bladder sits deep in the pelvis and has an intricate network of blood vessels. You can't just plug it in like a kidney. The surgeons had to figure out how to connect those vessels without damaging them, and that required years of practice on cadavers before they'd risk it on a living person.
And the alternative—using intestine—actually makes things worse for most people?
Yes. About 80 percent of patients who get the intestinal workaround develop serious complications. Your gut and your urinary system have completely different bacterial ecosystems. Forcing them to work together creates infections, digestive problems, sometimes kidney damage. A real bladder avoids all of that.
So why can't everyone who needs this just get a transplant now?
Because the patient has to take immunosuppressive drugs for life to prevent rejection. Those medications carry real risks—infections, cancer, organ damage over time. You only accept that trade-off if your current situation is dire. For Larrainzar, seven years on dialysis made it worth it.
What happens if the next four surgeries fail?
Then you learn something. You adjust the technique, you try again. But the team is confident enough to have already planned those four cases. They wouldn't do that if they thought this was a fluke.
And if they all succeed?
Then you're looking at a much larger trial, and eventually this becomes a real treatment option for people with terminal bladder disease. That's millions of people globally who suddenly have a path forward they didn't have before.